The relevant question might be: will IRCC be working on a particular individual's application such and such days?
The answer to this one is EASY, and it is PROBABLY NOT.
Be that a Sunday or Wednesday. No, it is very, very likely NO ONE is working on your application that day. Hundred to one odds, at the very least.
That answer is easy because applications mostly sit in a queue with NO ONE actively working on them for the vast, vast, vast majority of the time. For routinely processed applications, it is not likely much if any more than a couple or few hours TOTAL (if that much) is spent actually working on the application during the entire process, including all the time spent working on it from its arrival at CPC-Sydney to when the individual raises his or her hand and takes the oath.
Applicants are, so to say, standing in a long, long line . . . initially with thousands of others in line in front of them. It takes CPC-Sydney months to just open the application package. Months to open it, but in terms of actual time spent working on it, little more than a part-of-an-hour to actually open it, do the completeness check including a GCMS screening, open a GCMS application file, scan the application including outside packaging, and make referrals to CSIS and the RCMP, make and send AOR notations, and then the application goes back into queue. Maybe that takes more than an hour, but if so not by much.
There appears to be some additional screening at CPC-Sydney before the application is "In Process," but that almost certainly involves less than an hour of total time working on the file, including the act of referring and sending it to a local office, which includes making and sending the "In Process" notation.
After "In Process," for applications in most local offices, the application continues to be in line with thousands in front of it. It will be several MONTHS more before anyone actively does anything on the application. For MONTHS it is not likely anyone even looks at it, at all, unless the applicant does something to trigger an inquiry, in which event the sum and substance of what is done is that someone opens and looks at the applicant's GCMS records, responds to the inquiry, done, application back into queue.
The idea that IRCC is "working on" or "processing" a particular application mostly means that the particular application has an active status and is PENDING the next step. NOT that anyone is actively doing anything.